SWS Security
White Papers
"In God We Trust. All Others We Monitor."

Backup/Emergency Power Systems -- Generators

Emergency Generators

Some miscellaneous comments for anyone thinking of backup power for their home or work stations in the form of generators:

My father and I both went through the same independent research and arrived at the same conclusion as to generator brands. If youíre buying new, Honda is our choice. There are other quality brands, but Honda stands head and shoulders above the rest. I happened already to own a Generac and have been happy with it, but if I ever buy another one it will be a Honda. 7500 watts is about the largest you will find without getting into the large, professionally installed standby generator category. Honda recently has come out with a new and significantly improved line of generators (read this as Ďalternatorí actually).

Propane is a better generator fuel than gasoline. Donít overlook the need for *substantial* fuel storage. I chose gasoline, and my father chose propane. His is quieter, safer, less maintenance and preservative free. Gas needs an expensive preservative (formerly $50 for a gallon of preservative which protects 300 gallons of gas for 5 years; now better and cheaper stuff is available). If you go gasoline, you must use a high quality preservative. Gasoline will run the vehicles and farm equipment in addition to the generator, so I chose gasoline as the fuel I would store. Remember, buying a generator is only the beginning.

Calculate your power requirements, and be conservative. Donít forget starting current of large motors like air conditioners, fridge and freezer compressors and well pumps can be triple the running current. 7500 watts should run just about all of a large household even in the winter with some resistive heating. You can do the straightforward addition of the loads of the various things you may want to power. Important to me is freezer and fridge, well and septic pump, electric baseboard heat, three window air conditioners, security system, medical equipment, some radio communications gear, and computers. Push the generator too hard, and youíll trip out a phase.

You MUST have a transfer switch. I switch my entire house, barn and shop/office (3 separate buildings on adjacent properties) all on one 100 amp manual transfer switch, and turn on and off individual circuit breakers in the various electrical panels to control what gets powered up, as things change seasonally. Most people have a subpanel wired with any circuit they want to run on backup power. I chose to switch the entire house. You can not compromise on a transfer switch. Again, the generator is only one part of a backup power system.

We are in the country, and I canít just look over at the neighborís house to see his lights come back on to know when commercial power is restored. I donít like the idea of automatic transfer switches, as I donít like the generator coming on every time power drops for ten minutes as it does weekly out here, plus after a storm the power may bounce on and off a few times before settling in.

I wired a low voltage transformer ahead of the transfer switch directly to the incoming commercial power, and then the low voltage side to a squealer in the house with a switch. When we lose power, and I start the generator, I flip the switch. When commercial power is restored, minutes, hours or days later, the squealer sounds off and lets me know I can think about coming off generator. I give it about 20 minutes, and if commercial power holds, then I flip the transfer switch back to commercial, idle down the generator for 10 minutes (and when it comes up, I let it idle for 10 minutes before applying load), then shut off the fuel to let it run dry, and play choke games to get it to suck the last of the fumes. Mine is manual start as I didnít want to maintain a battery. Itís a one pull start 99% of the time.

Note: I ran low voltage to the squealer. This is for safety. If one of the buildings would catch on fire and the fire dept would pull the main switch for the premises, they have every right to expect all mains power to be removed. I went ahead of the main switch, but bring current limited 12VDC into the house for the squealer.

I run the generator 30 minutes once a month for maintenance. Worst thing you can do is have mechanics sit. 30 minutes once a week would be better. 30 minutes once a week is only 26 hours a year, and thatís nothing. A decent setup should be good for several thousand hours with only routine maintenance.

I added a mechanical hours meter made for a tractor, mounted in a wall bracket in the generator shed. I had to incorporate a smoothing RC circuit to let the hours meter run properly off the 12VDC generator output at idle. As purchased, it would run only when the generator was at speed, not at idle. I wanted an accurate reading of actual engine hours, for maintenance purposes.

Keep a logbook, spare air and oil filters, a half dozen pregapped spark plugs, a case or two of appropriate oil, and all necessary tools including a strap wrench for the oil filter hanging on nails in the generator room so you donít have to hunt for them in the middle of winter in the dark under pressure.

I placed both a dry chemical (for electrical) and large foam (for fuel) fire extinguisher on the wall next to each other in the generator shed. Put large signs on each stating FOR ELECTRIC, NOT FOR ELECTRIC plainly, for anyone else to read under stress in an emergency in low light.

If you go gasoline, buy the gasoline in the winter, as extra butane and other additives are added to winter gas to make cleaner emissions and easier winter starting. It is beneficial to have this extra butane, and they put it in only in the winter. The additives boil off over time, so you start with extra if you buy winter gas.

Iíve had my generator 6 years now (fall 2004), with a 275 gallon fuel tank placed on edge in a generator shack built on the side of my barn. The fuel tank is raised on pipe legs so the feed is at the level of the original tank, with split valves to feed both the generator and an external gas station type hose for fueling vehicles or farm equipment from the tank. The tank is high enough to gravity feed into any vehicle. The generator is mounted on an assembly of railroad ties bolted to the concrete floor, so the whole thing is up off the moist ground, permits airflow for cooling underneath and allows sufficient height for the fuel to gravity feed to the vehicles which have higher fill points than the generator. The extra height also is easier on my back during maintenance, and lets me get a pan under the oil drain. And if I drop a tool or a part, I can just reach underneath and fetch it instead of having to move a several hundred pound generator!

275 gallons of gas is enough to run the generator for 30 continuous days at half load. The longest Iíve run it is just a few hours short of 6 days, shutting it down for 5 minutes 2x/day to check oil level. I use 10W30 oil year round, which is the proper weight for winter. This is a fairly lightweight oil and results in a bit more oil consumption, but adds the benefit of better lubrication year round.

Every few years, I cycle the gas and use it in the vehicles. Iíll save the last 20 gallons until the beginning of winter when the extra additives are added, then drain the last, pour in the proper amount of preservative, and call Southern States to fill up the tank with fresh gasoline.

I had a fitting into a flexible coupler ($90 just for the coupler  ugh!) welded to the original muffler, and plumbed with standard exhaust pipe to a full size auto muffler hanging from the shed ceiling. A fiberglass wool insulated exhaust pipe comes out behind the barn, away from the house. We can barely hear the generator run, and thereís woods behind the barn so the neighbors canít hear either, not that theyíre close enough to matter. If possible, Iíve learned itís a good idea to keep a low profile with this sort of thing, or youíre going to have neighbors asking you to refrigerate their beer in the summer when no one has power.

I put fiberglass insulation on the walls, door and ceiling of the generator shed for sound reasons, and put a number of louvered vents and an electric fan to pull cooling air through and provide plenty of fresh air for the generator so it doesnít suck air out of the attached barn. I switch the fan on manually with the generator, and also with an X10 home automation circuit several hours a day to keep moisture down inside the generator shed. The large mass of gasoline causes sweating on the gas tank which I donít like. I added a compact fluorescent lamp in there on generator power, and several incandescent ones on commercial power, for maintenance purposes. Keep a large battery lantern handy to see at night until you get everything fired up.

I add a pint of alcohol to the fuel tank every few months to absorb any moisture which has condensed in the 275 gal tank. Very little will if you keep the tank full so there is no airspace. The alcohol, sold as gas line deicer, goes on sale in the spring after season for about 35 cents a pint. $20 worth is a lifetime supply. You must, of course, vent the fuel tank, through the roof with a long pipe and a hood over the end. You want a long vent pipe so gasoline fumes dissipate over a wide area rather than collect close to ground level.

And ground the generator and fuel tank. Concrete is an excellent conductor. I drove an 8 foot ground rod right next to the generator, poured the concrete slab floor around it, and strapped it both to the generator and fuel tank. Vibration causes sloshing of the gasoline in the tank which can build quite a static charge over time if not bled off. Drawing a spark could be a problem. Auto gas tanks have baffles to prevent sloshing and static buildup, plus carbon is added to the tires to ground the body and allow static to bleed off. Donít skip the ground. I keep a large piece of scrap denim over the generator when not in use, to keep it clean. I added an 8" extension tube to the oil drain so it can empty neatly into a pan instead of dripping down the frame.

I added my own twist lock connector to the 12VDC output of the generator and made a cord with large clips to charge 12 volt batteries. Might come in handy for charging batteries in a long term outage or emergency where portable communications batteries are used in the field.

Start and keep a logbook. Bind it somehow, with a copy of the generatorís instruction manual, and many pages of log sheets. Every time you start the generator for whatever reason, log the date, reason for operation, work done (oil change, etc.), comments, hours and fractions operated, and a running total of generator hours since installed.

Every time you touch the generator to operate it or maintain it you should log it. I bound all this in a spiral plastic covered book and keep a pencil tucked in the spine. Very good reference info all at hand if needed, and reminders of maintenance due or problems you note needing correction, maintenance performed, etc. as well as a history of outages, how much fuel consumed (make a log entry every time you add fuel and preservative to your tank) and so forth. Good recordkeeping is efficient and the sign of a professional operator.

I keep the logbook on top of the generator under the denim cover to keep it clean.

Main thing is:

1)   Donít overlook LARGE quantities of fuel, WITH preservative if you choose gasoline

2)   You MUST have a transfer switch

3)   You MUST have plenty of spare parts like filters and spark plugs, and the tools to change them, immediately at hand. Use a fuel filter and have spares!

4)   You MUST run the generator periodically to keep it in good shape. 30 minutes a week would be best, 30 minutes a month is the minimum.

5)   Buy a few cases of recommended oil, put it on a shelf near the generator, and change it very frequently. I change it every other month or after every outage, whichever is sooner. You canít change oil too often, and itís cheap maintenance.

(Comments from a reader of the above)

  • I plan on a Honda and already have found a lot of price diff from locally to an outfit in Maine. They have a natural gas propane model that can easily be changed I can have a outlet for the natural gas which we use to heat on the outside and just roll the generator up hook up the natural gas and electric and throw the switch I can have a couple of propane tanks for a back up. My father converted his from gasoline to propane.
  • As I mentioned, you can buy new Hondas factory set up for propane, and you can get dual fuel models. There is a difference between natural gas and bottled gas. Bottled gas is more potent and requires different jets in the carb. You have to choose one or the other. Natural gas or propane have less energy per unit compared to gasoline, so if you convert from gasoline you need to downrate the generator capacity by 30%.
  • Since one of the reasons for a generator is emergency power if utilities were down, I wouldnít consider using natural gas piped in by the outside world infrastructure as adequate. Bottled gas on site is the preferred way to go. Be sure to have enough of it. A small BBQ grillsized bottle probably would run your 7500 watt model at half load (the way they rate them) for maybe 2 or 3 hours max.

    If you used bottled gas, Iíd have half a dozen full BBQsized tanks, or the same of RV sized tanks. It goes quicker than you would expect, because there is less energy in propane than in gasoline. One advantage of smaller tanks is they would force you to shut down and check oil periodically.

    Our longest outage was a few hours short of 6 days. That would have taken probably 100 pounds of propane, and I think there is about 3 pounds to the gallon, or 30 gallons. I used about 20 gallons of gasoline over that 5 days, which is about right. That was fall, mild weather, where I was running neither heat nor air conditioning. I would have used significantly more fuel if weíd have been in weather extremes.

    You say Ďhook up the electricí. Itís not that simple. You must have a transfer switch, otherwise you could end up inadvertently feeding your power back into the grid and killing some poor wire guy repairing the downed lines. Your generator also wonít be happy trying to power your entire community, which will happen if you connect directly to the grid without a transfer switch. Amazingly, an enormous number of people do exactly this, and linesmen learn never, ever, to trust a downed line to be absent of power.

    Some people cheat by making a cord to plug the generator into the electric dryer 220 VAC outlet and backfeeding to the panel, and first turning off the main breaker. This is dangerous. Best is to install a transfer switch ahead of your main panel, where you SPDT the house either to commercial power (the electric meter) or the backup power (the generator).

    If there is bad weather, which is likely during a power failure, you are going to want the generator under roof. The generator will not be happy operating naked in a rainstorm or snowstorm, and neither will you when it comes time to service the thing. Garage is no good as the fumes from any fuel are toxic and houses arenít sealed well enough to keep the fumes out, plus the noise will drive you out of your mind.

    If nothing else, build an adequately sized lean to outside the house (remember it may be raining and snowing with high wind), away from the house, and preferably away from the sleeping areas. Believe me, the noise will get to you, especially if you are using the small muffler on the original generator. If you canít mount the generator permanently out there, you can wheel it there when needed. Remember in bad weather, like deep snow, itís not easy to pull a 300 pound generator through the snow on those little wheels.

    Propane is quieter than gasoline by maybe 1/3.

    The only gasoline preservative available when I first started using the stuff and originally wrote the above was StaBil. It is common in rural areas. Itís good stuff, but expensive. It adds a minimum of 50 cents per gallon to the cost of gasoline. It will preserve the gas a minimum of three years, and one gallon of StaBil treats 300 gallons of gasoline. You can retreat after 3 years, but itís far better to rotate the gasoline.

    Now two other brands of preservative have been developed. Iíve used both, and both are excellent. They are much cheaper compared to StaBil, and you need a much smaller volume. One quart treats 500+ gallons of gasoline, will renew old gas, can be refreshed, and overall seems to be a better product than StaBil.

    These brands are POR15 and PRIG (G for gasoline, D for diesel).



    I admit to having developed a preference for PRI products, but I cannot articulate why. Do some serious price shopping among various distributors, as prices can vary widely between different outlets. The preservative itself, if not mixed with gas, will store indefinitely.

    In the Harford County (Maryland) area, the place I buy generators is Jackís Small Engine Service in Jarrettsville, Maryland. They are competent, honest and open minded. Jackís stocks spare parts, does repairs and provides advice. Highly recommended.

    http://jackssmallengines.com or 4105576792

    Some Generator system components, like the transfer switch, need to be installed by a licensed, competent electrician. You need to pull the electric meter to do it properly. I can recommend a local electrician who covers York County, most of MD and probably elsewhere in PA. Ask me for his contact info. He did the legal part of my installation and is very easy to work with. If you want a custom exhaust system welded as I normally do, I recommend Moxleyís Welding at Routes 136 & 1 in Darlington, Maryland. They are masters and have been able to do anything Iíve needed.

    Above all else, remember you are installing a backup power system, and a generator is only one component of the system. Donít stop with just the generator or youíre only fooling yourself.

    Feel free to ask me any questions about anything relating to generator installation, operation or maintenance.

    Steve WA3SWS


emergency generator

Back to Whatís New